A flexible dense wavelength division multiplexing (DWDM) grid has been introduced in Edition 2.0 of the International Telecommunication Union (ITU) Recommendation ITU-T G.694.1 (February 2012).
The following references are further believed to represent the state of the art:
an article entitled “Spectrum-Efficient and Agile CO-OFDM Optical Transport Networks: Architecture, Design, and Operation”, by Gangxiang Shen and Moshe Zukerman, in IEEE Communications Magazine, May 2012, pages 82-89;
an article entitled “Spectrum-Efficient and Scalable Elastic Optical Path Network: Architecture, Benefits, and Enabling Technologies”, by Masahiko Jinno, Hidehiko Takara, Bartlomiej Kozicki, Yukio Tsukishima, Yoshiaki Sone, and Shinji Matsuoka, in IEEE Communications Magazine, November 2009, pages 66-73;
an article entitled “Flexible Architectures for Optical Transport Nodes and Networks”, by Steven Gringeri, Bert Basch, Vishnu Shukla, Roman Egorov, and Tiejun J. Xia, in IEEE Communications Magazine, July 2010, pages 40-50;
an article entitled “100G and Beyond with Digital Coherent Signal Processing”, by Kim Roberts, Douglas Beckett, David Boertjes, Joseph Berthold, and Charles Laperle, in IEEE Communications Magazine, July 2010, pages 62-69;
an article entitled “Elastic Optical Networking: A New Dawn for the Optical Layer?”, by Ori Gerstel, Masahiko Jinno, Andrew Lord, and S. J. Ben Yoo, in IEEE Communications Magazine, February 2012, pages S12-S20;
an article entitled “IETF Work on Protection and Restoration for Optical Networks”, by David W. Griffith in Optical Networks Magazine, July/August 2003, pages 101-106; and
an Internet Draft draft-ietf-ccamp-gmpls-recovery-functional-03.txt entitled “Generalized Multi-Protocol Label Switching (GMPLS) Recovery Functional Specification”, of the Network Working Group, edited by Jonathan P. Lang and Bala Rajagopalan and dated October 2004.